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		<p class="post-meta">
		<time class="dt-published" datetime="2019-03-29T00:00:00-04:00" itemprop="datePublished">Friday, March 29, 2019
		</time>• by <span itemprop="author" itemscope itemtype="http://schema.org/Person"><span class="p-author h-card" itemprop="name">Ron Tarrant</span></span></p>
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		<h1 id="0022-building-a-grid-with-a-gtk-grid">0022: Building a Grid with a <em>GTK</em>… Grid</h1>

<p>Taking <a href="./0021-labels-with-background-colors-markup.html">the subject of the last blog post</a> a bit further, we’re going to look at <code class="language-plaintext highlighter-rouge">Label</code>s again, but in another type of container, the <code class="language-plaintext highlighter-rouge">Grid</code>.</p>

<p>How many rows and/or columns are in a grid? It depends on how many cells you stuff in there. You don’t pre-define the number of rows and columns. Instead, the <code class="language-plaintext highlighter-rouge">Grid</code> redefines its layout as cells are added. Put a cell into position <strong>0, 0</strong> and you’ve got one row, one column. Follow this with another cell at position <strong>0, 1</strong> and you’ve got two rows, but still only one column. And you should be able to extrapolate from there… <strong>1, 0</strong> gives you two rows, two columns with cell <strong>1, 1</strong> empty, etc.</p>

<h2 id="the-basic-grid">The Basic Grid</h2>

<div class="screenshot-frame">
	<div class="frame-header">
		Results of this example:
	</div>
	<div class="frame-screenshot">
		<figure>
			<img id="img0" src="../images/screenshots/009_grid/grid_01.png" alt="Current example output" />		<!-- img# -->
			
			<!-- Modal for screenshot -->
			<div id="modal0" class="modal">																	<!-- modal# -->
				<span class="close0">&times;</span>															<!-- close# -->
				<img class="modal-content" id="img00" />															<!-- img## -->
				<div id="caption"></div>
			</div>
			
			<script>
			// Get the modal
			var modal = document.getElementById("modal0");														// modal#
			
			// Get the image and insert it inside the modal - use its "alt" text as a caption
			var img = document.getElementById("img0");															// img#
			var modalImg = document.getElementById("img00");													// img##
			var captionText = document.getElementById("caption");

			img.onclick = function()
			{
			  modal.style.display = "block";
			  modalImg.src = this.src;
			  captionText.innerHTML = this.alt;
			}
			
			// Get the <span> element that closes the modal
			var span = document.getElementsByClassName("close0")[0];											// close#
			
			// When the user clicks on <span> (x), close the modal
			span.onclick = function()
			{ 
				modal.style.display = "none";
			}
			</script>
			<figcaption>
			Current example output
			</figcaption>
		</figure>
	</div>

	<div class="frame-terminal">
		<figure class="right">
			<img id="img1" src="../images/screenshots/009_grid/grid_01_term.png" alt="Current example terminal output" />		<!-- img#, filename -->

			<!-- Modal for terminal shot -->
			<div id="modal1" class="modal">																				<!-- modal# -->
				<span class="close1">&times;</span>																		<!-- close# -->
				<img class="modal-content" id="img11" />																		<!-- img## -->
				<div id="caption"></div>
			</div>
			
			<script>
			// Get the modal
			var modal = document.getElementById("modal1");																	// modal#
			
			// Get the image and insert it inside the modal - use its "alt" text as a caption
			var img = document.getElementById("img1");																		// img#
			var modalImg = document.getElementById("img11");																// img##
			var captionText = document.getElementById("caption");

			img.onclick = function()
			{
			  modal.style.display = "block";
			  modalImg.src = this.src;
			  captionText.innerHTML = this.alt;
			}
			
			// Get the <span> element that closes the modal
			var span = document.getElementsByClassName("close1")[0];														// close#
			
			// When the user clicks on <span> (x), close the modal
			span.onclick = function()
			{ 
				modal.style.display = "none";
			}
			</script>

			<figcaption>
				Current example terminal output (click for enlarged view)
			</figcaption>
		</figure>
	</div>

	<div class="frame-footer">																								<!-- ------------- filename (below) --------- -->
		The code file for this example is available <a href="https://github.com/rontarrant/gtkd_demos/blob/master/009_grid/grid_01_checkerboard.d" target="_blank">here</a>.
	</div>
</div>

<p>In this example, we stuff cells into the <code class="language-plaintext highlighter-rouge">Grid</code> “longhand” by defining each one and sticking it into a specific position within the <code class="language-plaintext highlighter-rouge">Grid</code>. I did this example this way because the second one—which pushes the cells in using a pair of <code class="language-plaintext highlighter-rouge">for</code> loops—gets a bit cryptic, not making it clear how cells within the <code class="language-plaintext highlighter-rouge">Grid</code> are numbered.</p>

<p>Let’s dive in, shall we?</p>

<h3 id="a-new-type-of-mainwindow">A New Type of MainWindow</h3>

<p>This time around, I dropped the <code class="language-plaintext highlighter-rouge">TestRigWindow</code> class and cut right to the chase, defining a <code class="language-plaintext highlighter-rouge">GridWindow</code> class derived from the <code class="language-plaintext highlighter-rouge">MainWindow</code> superclass. From there, it was just a matter of setting up a <code class="language-plaintext highlighter-rouge">Grid</code>, sticking things into each cell of the <code class="language-plaintext highlighter-rouge">Grid</code>, and then tossing that into the <code class="language-plaintext highlighter-rouge">GridWindow</code>. Easy.</p>

<p>And the cell stuffing was done, as mentioned earlier, by hand. Here are the first two rows:</p>

<div class="language-d highlighter-rouge"><div class="highlight"><pre class="highlight"><code><span class="c1">// row 0</span>
<span class="n">RedLabel</span> <span class="n">zeroZero</span> <span class="p">=</span> <span class="k">new</span> <span class="n">RedLabel</span><span class="p">(</span><span class="s">"cell 0, 0"</span><span class="p">);</span>
<span class="n">grid</span><span class="p">.</span><span class="n">attach</span><span class="p">(</span><span class="n">zeroZero</span><span class="p">,</span> <span class="mi">0</span><span class="p">,</span> <span class="mi">0</span><span class="p">,</span> <span class="mi">1</span><span class="p">,</span> <span class="mi">1</span><span class="p">);</span>
<span class="n">BlueLabel</span> <span class="n">oneZero</span> <span class="p">=</span> <span class="k">new</span> <span class="n">BlueLabel</span><span class="p">(</span><span class="s">"cell 1, 0"</span><span class="p">);</span>
<span class="n">grid</span><span class="p">.</span><span class="n">attach</span><span class="p">(</span><span class="n">oneZero</span><span class="p">,</span> <span class="mi">1</span><span class="p">,</span> <span class="mi">0</span><span class="p">,</span> <span class="mi">1</span><span class="p">,</span> <span class="mi">1</span><span class="p">);</span>
<span class="n">RedLabel</span> <span class="n">twoZero</span> <span class="p">=</span> <span class="k">new</span> <span class="n">RedLabel</span><span class="p">(</span><span class="s">"cell 2, 0"</span><span class="p">);</span>
<span class="n">grid</span><span class="p">.</span><span class="n">attach</span><span class="p">(</span><span class="n">twoZero</span><span class="p">,</span> <span class="mi">2</span><span class="p">,</span> <span class="mi">0</span><span class="p">,</span> <span class="mi">1</span><span class="p">,</span> <span class="mi">1</span><span class="p">);</span>
<span class="n">BlueLabel</span> <span class="n">threeZero</span> <span class="p">=</span> <span class="k">new</span> <span class="n">BlueLabel</span><span class="p">(</span><span class="s">"cell 3, 0"</span><span class="p">);</span>
<span class="n">grid</span><span class="p">.</span><span class="n">attach</span><span class="p">(</span><span class="n">threeZero</span><span class="p">,</span> <span class="mi">3</span><span class="p">,</span> <span class="mi">0</span><span class="p">,</span> <span class="mi">1</span><span class="p">,</span> <span class="mi">1</span><span class="p">);</span>

<span class="c1">// row 1</span>
<span class="n">BlueLabel</span> <span class="n">zeroOne</span> <span class="p">=</span> <span class="k">new</span> <span class="n">BlueLabel</span><span class="p">(</span><span class="s">"cell 0, 1"</span><span class="p">);</span>
<span class="n">grid</span><span class="p">.</span><span class="n">attach</span><span class="p">(</span><span class="n">zeroOne</span><span class="p">,</span> <span class="mi">0</span><span class="p">,</span> <span class="mi">1</span><span class="p">,</span> <span class="mi">1</span><span class="p">,</span> <span class="mi">1</span><span class="p">);</span>
<span class="n">RedLabel</span> <span class="n">oneOne</span> <span class="p">=</span> <span class="k">new</span> <span class="n">RedLabel</span><span class="p">(</span><span class="s">"cell 1, 1"</span><span class="p">);</span>
<span class="n">grid</span><span class="p">.</span><span class="n">attach</span><span class="p">(</span><span class="n">oneOne</span><span class="p">,</span> <span class="mi">1</span><span class="p">,</span> <span class="mi">1</span><span class="p">,</span> <span class="mi">1</span><span class="p">,</span> <span class="mi">1</span><span class="p">);</span>
<span class="n">BlueLabel</span> <span class="n">twoOne</span> <span class="p">=</span> <span class="k">new</span> <span class="n">BlueLabel</span><span class="p">(</span><span class="s">"cell 2, 1"</span><span class="p">);</span>
<span class="n">grid</span><span class="p">.</span><span class="n">attach</span><span class="p">(</span><span class="n">twoOne</span><span class="p">,</span> <span class="mi">2</span><span class="p">,</span> <span class="mi">1</span><span class="p">,</span> <span class="mi">1</span><span class="p">,</span> <span class="mi">1</span><span class="p">);</span>
<span class="n">RedLabel</span> <span class="n">threeOne</span> <span class="p">=</span> <span class="k">new</span> <span class="n">RedLabel</span><span class="p">(</span><span class="s">"cell 3, 1"</span><span class="p">);</span>
<span class="n">grid</span><span class="p">.</span><span class="n">attach</span><span class="p">(</span><span class="n">threeOne</span><span class="p">,</span> <span class="mi">3</span><span class="p">,</span> <span class="mi">1</span><span class="p">,</span> <span class="mi">1</span><span class="p">,</span> <span class="mi">1</span><span class="p">);</span>
</code></pre></div></div>

<p>And as I implied in the last post, we now have a <code class="language-plaintext highlighter-rouge">BlueLabel</code> as well as a <code class="language-plaintext highlighter-rouge">RedLabel</code> (shades of <em>that whisky everyone raves about</em>). Here’s the super-class they’re derived from:</p>

<div class="language-d highlighter-rouge"><div class="highlight"><pre class="highlight"><code><span class="k">class</span> <span class="n">WideLabel</span> <span class="p">:</span> <span class="n">EventBox</span>
<span class="p">{</span>
	<span class="n">Label</span> <span class="n">label</span><span class="p">;</span>
	
	<span class="k">this</span><span class="p">(</span><span class="nb">string</span> <span class="n">text</span><span class="p">)</span>
	<span class="p">{</span>
			<span class="k">super</span><span class="p">();</span>
			
			<span class="n">label</span> <span class="p">=</span> <span class="k">new</span> <span class="n">Label</span><span class="p">(</span><span class="n">text</span><span class="p">);</span>
			<span class="n">label</span><span class="p">.</span><span class="n">setSizeRequest</span><span class="p">(</span><span class="mi">60</span><span class="p">,</span> <span class="mi">60</span><span class="p">);</span>
			<span class="n">add</span><span class="p">(</span><span class="n">label</span><span class="p">);</span>
			
	<span class="p">}</span> <span class="c1">// this()</span>
	
<span class="p">}</span> <span class="c1">// class WideLabel</span>
</code></pre></div></div>

<p>I suppose I should have called it <code class="language-plaintext highlighter-rouge">ColorLabel</code>, but the code’s written now and I’m tired, so <code class="language-plaintext highlighter-rouge">WideLabel</code> it is. What sets this class apart from the <code class="language-plaintext highlighter-rouge">RedLabel</code> of yore (and made me think to call it <em>Wide</em>) is that I hard-coded the <code class="language-plaintext highlighter-rouge">Label</code> size. Rather than using extra space on either side of the text and blank lines above and below, I got all sophisticated and called <code class="language-plaintext highlighter-rouge">setSizeRequest()</code> to make all the <code class="language-plaintext highlighter-rouge">Labels</code> (and therefore the cells) a specific, uniform size.</p>

<p>The <code class="language-plaintext highlighter-rouge">RedLabel</code> looks very much the same as before—other than its size—and <code class="language-plaintext highlighter-rouge">BlueLabel</code> is the same except… well, it’s blue.</p>

<p>And don’t overlook the extra imports at the top of the file, some of which we used last time, too:</p>

<div class="language-d highlighter-rouge"><div class="highlight"><pre class="highlight"><code><span class="k">import</span> <span class="n">gtk</span><span class="p">.</span><span class="n">Grid</span><span class="p">;</span>
<span class="k">import</span> <span class="n">gtk</span><span class="p">.</span><span class="n">EventBox</span><span class="p">;</span>
<span class="k">import</span> <span class="n">gtk</span><span class="p">.</span><span class="n">RGBA</span><span class="p">;</span>
</code></pre></div></div>

<ul>
  <li>The <code class="language-plaintext highlighter-rouge">Grid</code> import is self-explanatory.</li>
  <li>But the <code class="language-plaintext highlighter-rouge">EventBox</code>, which one might think would be imported from <em>GDK</em> rather than <em>GTK</em>, in fact, bucks the trend.</li>
  <li><code class="language-plaintext highlighter-rouge">RGBA</code> lets us define a colour, and</li>
  <li>the comment below the import statements mentions that <code class="language-plaintext highlighter-rouge">StateFlags</code> are found in <code class="language-plaintext highlighter-rouge">c.types</code>.</li>
</ul>

<h2 id="defining-a-grid-the-shorthand-way">Defining a Grid the Shorthand Way</h2>

<div class="screenshot-frame">
	<div class="frame-header">
		Results of this example:
	</div>
	<div class="frame-screenshot">
		<figure>
			<img id="img2" src="../images/screenshots/009_grid/grid_02.png" alt="Current example output" />		<!-- img# -->
			
			<!-- Modal for screenshot -->
			<div id="modal2" class="modal">																<!-- modal# -->
				<span class="close2">&times;</span>														<!-- close# -->
				<img class="modal-content" id="img22" />														<!-- img## -->
				<div id="caption"></div>
			</div>
			
			<script>
			// Get the modal
			var modal = document.getElementById("modal2");													// modal#
			
			// Get the image and insert it inside the modal - use its "alt" text as a caption
			var img = document.getElementById("img2");														// img#
			var modalImg = document.getElementById("img22");												// img##
			var captionText = document.getElementById("caption");

			img.onclick = function()
			{
			  modal.style.display = "block";
			  modalImg.src = this.src;
			  captionText.innerHTML = this.alt;
			}
			
			// Get the <span> element that closes the modal
			var span = document.getElementsByClassName("close2")[0];										// close#
			
			// When the user clicks on <span> (x), close the modal
			span.onclick = function()
			{ 
				modal.style.display = "none";
			}
			</script>
			<figcaption>
			Current example output
			</figcaption>
		</figure>
	</div>

	<div class="frame-terminal">
		<figure class="right">
			<img id="img3" src="../images/screenshots/009_grid/grid_02_term.png" alt="Current example terminal output" /> 		<!-- img#, filename -->

			<!-- Modal for terminal shot -->
			<div id="modal3" class="modal">																			<!-- modal# -->
				<span class="close3">&times;</span>																	<!-- close# -->
				<img class="modal-content" id="img33" />																	<!-- img## -->
				<div id="caption"></div>
			</div>
			
			<script>
			// Get the modal
			var modal = document.getElementById("modal3");																// modal#
			
			// Get the image and insert it inside the modal - use its "alt" text as a caption
			var img = document.getElementById("img3");																	// img#
			var modalImg = document.getElementById("img33");															// img##
			var captionText = document.getElementById("caption");

			img.onclick = function()
			{
			  modal.style.display = "block";
			  modalImg.src = this.src;
			  captionText.innerHTML = this.alt;
			}
			
			// Get the <span> element that closes the modal
			var span = document.getElementsByClassName("close3")[0];													// close#
			
			// When the user clicks on <span> (x), close the modal
			span.onclick = function()
			{ 
				modal.style.display = "none";
			}
			</script>

			<figcaption>
				Current example terminal output (click for enlarged view)
			</figcaption>
		</figure>
	</div>

	<div class="frame-footer">																							<!--------- filename (below) ------------>
		The code file for this example is available <a href="https://github.com/rontarrant/gtkd_demos/blob/master/009_grid/grid_02_checkerboard_alternate.d" target="_blank">here</a>.
	</div>
</div>

<p>Now let’s look at some of the bits and bobs in there. The results of all this code are the same as with our first example, but getting there via a different route. Here’s the constructor, which is the essence of things:</p>

<div class="language-d highlighter-rouge"><div class="highlight"><pre class="highlight"><code><span class="k">this</span><span class="p">()</span>
<span class="p">{</span>
	<span class="kt">int</span> <span class="n">x</span><span class="p">,</span> <span class="n">y</span><span class="p">;</span> <span class="c1">// positions within the grid</span>
	<span class="kt">int</span> <span class="n">xOddEven</span><span class="p">,</span> <span class="n">yOddEven</span><span class="p">;</span>
	<span class="nb">string</span> <span class="n">labelText</span><span class="p">;</span>
	
	<span class="k">super</span><span class="p">(</span><span class="n">title</span><span class="p">);</span>
	
	<span class="n">grid</span> <span class="p">=</span> <span class="k">new</span> <span class="n">Grid</span><span class="p">();</span>
	
	<span class="k">foreach</span><span class="p">(</span><span class="kt">int</span> <span class="n">x</span><span class="p">;</span> <span class="mf">0..4</span><span class="p">)</span>
	<span class="p">{</span>
		<span class="k">foreach</span><span class="p">(</span><span class="kt">int</span> <span class="n">y</span><span class="p">;</span> <span class="mf">0..4</span><span class="p">)</span>
		<span class="p">{</span>
			<span class="n">xOddEven</span> <span class="p">=</span> <span class="n">x</span> <span class="p">%</span> <span class="mi">2</span><span class="p">;</span> <span class="c1">// row # odd or even?</span>
			<span class="n">yOddEven</span> <span class="p">=</span> <span class="n">y</span> <span class="p">%</span> <span class="mi">2</span><span class="p">;</span> <span class="c1">// column # odd or even?</span>
			<span class="n">labelText</span> <span class="p">=</span> <span class="n">format</span><span class="p">(</span><span class="s">"cell %d, %d"</span><span class="p">,</span> <span class="n">x</span><span class="p">,</span> <span class="n">y</span><span class="p">);</span>
			
			<span class="k">if</span><span class="p">((</span><span class="n">xOddEven</span> <span class="p">==</span> <span class="mi">0</span> <span class="p">&amp;&amp;</span> <span class="n">yOddEven</span> <span class="p">==</span> <span class="mi">0</span><span class="p">)</span> <span class="p">||</span> <span class="p">(</span><span class="n">xOddEven</span> <span class="p">!=</span> <span class="mi">0</span> <span class="p">&amp;&amp;</span> <span class="n">yOddEven</span> <span class="p">!=</span> <span class="mi">0</span> <span class="p">))</span>
			<span class="p">{</span>
				<span class="n">RedLabel</span> <span class="n">label</span> <span class="p">=</span> <span class="k">new</span> <span class="n">RedLabel</span><span class="p">(</span><span class="n">labelText</span><span class="p">);</span>
				<span class="n">labels</span> <span class="p">~=</span> <span class="n">label</span><span class="p">;</span> <span class="c1">// add in scope</span>
				<span class="n">grid</span><span class="p">.</span><span class="n">attach</span><span class="p">(</span><span class="n">label</span><span class="p">,</span> <span class="n">x</span><span class="p">,</span> <span class="n">y</span><span class="p">,</span> <span class="mi">1</span><span class="p">,</span> <span class="mi">1</span><span class="p">);</span> <span class="c1">// use in scope</span>
			<span class="p">}</span>
			<span class="k">else</span>
			<span class="p">{</span>
				<span class="n">BlueLabel</span> <span class="n">label</span> <span class="p">=</span> <span class="k">new</span> <span class="n">BlueLabel</span><span class="p">(</span><span class="n">labelText</span><span class="p">);</span>
				<span class="n">labels</span> <span class="p">~=</span> <span class="n">label</span><span class="p">;</span>
				<span class="n">grid</span><span class="p">.</span><span class="n">attach</span><span class="p">(</span><span class="n">label</span><span class="p">,</span> <span class="n">x</span><span class="p">,</span> <span class="n">y</span><span class="p">,</span> <span class="mi">1</span><span class="p">,</span> <span class="mi">1</span><span class="p">);</span>
			<span class="p">}</span>
		<span class="p">}</span>
	<span class="p">}</span>

	<span class="n">add</span><span class="p">(</span><span class="n">grid</span><span class="p">);</span>
	
<span class="p">}</span> <span class="c1">// this()</span>
</code></pre></div></div>

<p>It’s a bit of a mind-bender to follow, but the long and short of it is:</p>

<ul>
  <li>where the row and column numbers are both odd or both even, squares are red (that’s the <code class="language-plaintext highlighter-rouge">if</code> statement)</li>
  <li>where one is odd and the other even, squares are blue (that’s the <code class="language-plaintext highlighter-rouge">else</code>)</li>
  <li>x = rows</li>
  <li>y = columns</li>
</ul>

<p>And, in case you’ve never come across the <em>D</em>-style <code class="language-plaintext highlighter-rouge">foreach()</code>, it’s kind of cool because you can replace <code class="language-plaintext highlighter-rouge">for(int x; x &lt; 4; x++)</code> with <code class="language-plaintext highlighter-rouge">foreach(int x; 0..4)</code>. It’s less typing and, IMO, rather elegant. You can still use the <code class="language-plaintext highlighter-rouge">for()</code> construct if you want, though, so it’s up to you which you pick.</p>

<p>And that wraps up another adventure in <em>GtkD</em> coding-land. Bye for now.</p>

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